Return VkResult in vmaInvalidateAllocation and vmaFlushAllocation
Return VkResult in vmaInvalidateAllocation and vmaFlushAllocation

Fixes #120

GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator,GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator,GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator